The present invention relates to a heat-developable photosensitive material and a method of processing the same.
In recent years, reduction in wastes of processing solutions for photographic materials has been strongly desired from the viewpoints of environmental conservation and space saving in the medical field. Therefore, new technologies regarding light-sensitive heat-developable photographic materials used for medical diagnosis and photographic technology, which can be efficiently exposed by means of a laser image setter or a laser imager and form clear black images having high resolution and high sharpness, have been desired. It is possible for such light-sensitive heat-developable photographic materials to eliminate the necessity of using solutions of processing chemicals and to supply simpler and environmentally friendly heat-developable processing systems for customers Although such requirements are also present in the field of common image-forming materials, images for medical use are required to have high qualities including excellent sharpness and graininess, because fine depiction is essential to them. Also, they have a feature that it is desirable to have a cold black tone from a viewpoint of ease of diagnosis. At present, various kinds of hard copy systems utilizing pigment or dye, for example, inkjet printers and electrophotography, are distributed as common image-forming systems, but they are not satisfactory as output systems of images for medical use.
On the other hand, thermal image formation systems utilizing organic silver salts are described, e.g., in U.S. Pat. Nos. 3,152,904 and 3,457,075, and B. Shely, Thermally Processed Silver Systems in Imaging Processes and Materials, Neblette""s 8th Edition, compiled by Sturge, V. Walworth and A, Shepp, page 2 (1996). In particular, a heat-developable photosensitive material ordinarily has a light-sensitive layer containing a binder matrix dispersed therein a catalytic amount of photocatalyst (e.g., silver halide), a reducing agent, a reducible silver salt (e.g., an organic silver salt) and, if desired, a toning agent for controlling color tone of silver. After imagewise exposure, the heat-developable photosensitive material is heated at a high temperature (e.g., 80xc2x0 C. or higher) to cause a redox reaction between the silver halide or reducible silver salt (acting as an oxidizing agent) and the reducing agent, thereby forming a black silver image. The redox reaction is accelerated by the catalytic action of a latent image of the silver halide formed upon the image exposure. Thus, the black silver image is formed in the exposed area. The heat-developable photosensitive materials are described in many documents including U.S. Pat. No. 2,910,377 and JP-B-43-4924 (the term xe2x80x9cJP-Bxe2x80x9d as used herein means an xe2x80x9cexamined Japanese patent publicationxe2x80x9d). Also, Fuji Medical Dry Imager FM-DP L is available as a medical image formation system utilizing heat-developable photosensitive materials.
Such an imager for processing heat-developable photosensitive materials has a tray to stock unexposed photosensitive materials. On the ground of stocking various sizes of photosensitive materials or for the purpose of reducing the trouble of replacement of photosensitive materials, imagers having two trays have been developed and are launched on the market by various manufacturers. However, to further increase the number of trays is the requirement of the market. In order to increase the number of trays, it is inevitable to place a tray for photosensitive materials in the position closer to the floor as compared with conventional machines. Thus, the desired number of trays is ensured while keeping the total height of machine. However, the placing of a tray for photosensitive materials in the position closer to the floor causes an inherent trouble due to dust. Since the density of naturally occurring dust increases with coming close to the floor, the dust gets into the tray for photosensitive materials with opening and closing of the tray. Therefore, it has been desired to solve problems, for example, white spots on images and unevenness of density, which occur at exposure to light and heat-development of the photosensitive materials.
Therefore, an object of the invention is to provide a heat-developable photosensitive material having surface characteristics of-effectively preventing from adhesion of dust, which is inherently present in large amounts in the area close to the floor.
Another object of the invention is to provide a method of processing such a heat-developable photosensitive material.
Other objects of the invention will become apparent from the following description.
The objects of the invention can be accomplished by a heat-developable photosensitive material and a method of processing the same as described below.
(1) A heat-developable photosensitive material, which comprises a light-sensitive layer containing a light-sensitive silver halide, a light-insensitive organic silver salt, a thermal developer and a binder and a protective layer containing a fluorine compound having at least one fluorinated alkyl group having not less than 2 carbon atoms and not more than 13 fluorine atoms and at least one anionic or nonionic hydrophilic group, and is subjected to processing by a heat-developing machine having a stock tray for heat-developable photosensitive materials placed at the height of not more than 55 cm above the floor.
(2) The heat-developable photosensitive material as described in item (1) above, wherein the heat-developing machine has an exposure section for the heat-developable photosensitive material arranged above the stock tray for heat-developable photosensitive materials.
(3) The heat-developable photosensitive material as described in item (1) or (2) above, wherein the heat-developing machine has at least 3 stock trays for heat-developable photosensitive materials.
(4) The heat-developable photosensitive material as described in any one of items (1) to (3) above, wherein the fluorine compound is a compound represented by the following formula (F): 
In formula (F), R1 and R2 each represent a substituted or unsubstituted alkyl group, provided that at least one of R1 and R2 represents a fluorinated alkyl group having not less than 2 carbon atoms and not more than 13 fluorine atoms; R3 and R4 each represent a hydrogen atom or a substituted or unsubstituted alkyl group; A represents xe2x80x94Lbxe2x80x94SO3M; M represents a hydrogen atom, a metallic atom or an ammonium group; and Lb represents a single bond or a substituted or unsubstituted alkylene group.
(5) The heat-developable photosensitive material as described in item (4) above, wherein both R3 and R4 in the compound represented by formula (F) represent hydrogen atoms.
(6) The heat-developable photosensitive material as described in item (4) or (5) above, wherein Lb in the compound represented by formula (F) represents a xe2x80x94CH2xe2x80x94 group.
(7) The heat-developable photosensitive material as described in any one of items (4) to (6) above, wherein at least one of R1 and R2 in the compound represented by formula (F) represents a fluorinated alkyl group having not less than 4 carbon atoms and not more than 11 fluorine atoms.
(8) The heat-developable photosensitive material as described in any one of items (4) to (7) above, wherein R1 and R2 in the compound represented by formula (F) each represent a fluorinated alkyl group having not less than 4 carbon atoms and not more than 11 fluorine atoms.
(9) A method of processing a heat-developable photosensitive material comprising processing a heat-developable photosensitive material, which comprises a light-sensitive layer containing a light-sensitive silver halide, a light-insensitive organic silver salt, a thermal developer and a binder and a protective layer containing a fluorine compound having at least one fluorinated alkyl group having not less than 2 carbon atoms and not more than 13 fluorine atoms and at least one anionic or nonionic hydrophilic group by a heat-developing machine having a stock tray for heat-developable photosensitive materials placed at the height of not more than 55 cm above the floor.